This invention relates to apparatus for cooling an internal combustion engine, especially in a motor vehicle, having a thermostatic valve for controlling the coolant flow from and to the combustion engine via a direct return or via a radiator, and having at least one fan associated with the radiator. This fan (or fans) can, as a function of at least one lower and one higher coolant temperature, be operated in at least two output stages (i.e., at least two fan operating modes having lower and higher respective output levels are provided).
In apparatus of this type, the thermostatic valve affects the temperature of the coolant and, thus, the temperature of the combustion engine by determining the temperature level at which it unblocks the connection to the radiator. In order to reduce the fuel consumption of the internal combustion engine, it is provided that the fan associated with the radiator is switched on only when it is required, i.e., when the temperature of the coolant and, thus, the temperature of the engine exceed a certain value. In this case, it is customary to operate the fan at several power levels or output stages, with the lowest output stages of the fan being assigned to a lower coolant temperature. Thus, when the temperature of the coolant increases, the fan will then be operated at a higher output stage. An object of this invention is to provide apparatus of the above-described type which allows the operating temperature of the internal combustion engine to be changed or adjusted, while preventing unnecessary consumption of output power by the fan.
This objective is achieved by providing a thermostatic valve which can be adjusted to at least two different opening temperatures, and by providing switching means for blocking the operation of the fan in the output stage associated with the lower coolant temperature when the thermostatic valve is adjusted to open at the higher coolant temperature.
The arrangement makes possible the adjustment of the engine temperature by means of different opening temperatures of the thermostatic valve, especially for optimizing the operation of the internal combustion engine. For example, it may be provided that in winter, as a function of the low outside temperatures, the thermostatic valve is adjusted in such a way that the internal combustion engine operates at a higher temperature. To avoid partially offsetting the effect of the increase in temperature, and also to avoid an increase in power consumption, it is provided in this case that the fan associated with the radiator does not operate at the lower coolant temperature at which it would normally start when the internal combustion engine is operated at the lower temperature level.
In an advantageous embodiment of the invention, an electric control element is provided for adjusting the thermostatic valve and a fan is electrically driven in at least the lower output stage which corresponds to the lower coolant temperature. A relay, which is controlled by the same signal transmitter which controls the electric control element, provides a switching contact in the electric feed line for the lower output stage.
In an especially advantageous embodiment of the invention, the thermostatic valve comprises a thermostatic working element having a housing to which is attached a valve disk. The valve disk cooperates with a valve seat to form a valve in the flow line leading to the radiator. The thermostatic valve also has a working piston extendable from the working element when the element is heated. The free end of the piston is adjacent to a support surface, the position of which can be adjusted in such a way that the distance from a support point on the surface to the piston end can be adjusted. With this arrangement, it is possible to use a thermostatic valve of conventional construction without necessitating modification of its structure, with the possible exception of a lengthening of the working piston.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, embodiments in accordance with the present invention.